Potion Giving Procedure

Hi everybody.

I'm making a key binding, which, when key pressed and you have specific armor (potion bag), it takes a bottle from your inventory and gives you specific potion (let's talk about regeneration in this case). I think I would be able to do it normally, just:

If is item in armor slot 2 of event entity potion bag and has event entity bottle in inventory,

remove 1 botttle from event entity's inventory and add 1 Regen potion to event entity's invnetory (and deal 1 damage to item in armor slot 2 of event entity).

But the problem is that I must set the damage of potion to pick which potion is it supposed to be and I don't know how.

Thanks in advance.